1. Field of the Invention
The present invention relates to an ink-jet recording apparatus in which insoluble materials originating from rubber members employed in an ink passage are prevented from precipitating into a water-based ink or a preservation solution filled into the ink passage.
2. Description of the Related Art
An ink-jet recording apparatus is an apparatus for performing recording by causing ink to adhere to a recording material such as recording paper by means of an ink ejection method such as a thermal method or a piezo method. In the thermal method, ink is rapidly heated to generate bubbles, and fine droplets of the ink are ejected from fine nozzles by utilizing the pressure generated by the rapid heating. In the piezo method, fine droplets of ink are ejected by use of a piezoelectric element.
In an ink-jet recording apparatus, rubber members are employed in an ink passage comprised of an ink tank, an ink-jet head and the ink. These rubber members include, but are not limited to, a cap which covers nozzles of the ink-jet head, a wiper which cleans the end face of the nozzles of the ink-jet head, a seal packing which is placed at the joint portion between components, and the like. In addition, if the ink tank is provided separately from the ink-jet head, the rubber members also include a tube which supplies ink from the ink tank to the ink-jet head, and the like.
However, when the rubber members come in contact with a water-based ink (hereinafter simply referred to as an ink) employed in ink-jet recording or with a preservation solution filled into an ink passage at the time of shipping or during long-term storage, the additives contained in the rubber members are dissolved in the ink or the preservation solution. The dissolved additives then precipitate as an insoluble material, thereby causing a problem such as clogging of nozzles of an ink-jet head.
In view of the above, a method has been proposed in US-A1-2005116984. In this method, rubber materials to be employed in an ink passage are immersed in water at 60° C. for a predetermined time in a sealed container for determining the amount of dissolved materials to thereby select suitable rubber materials.
However, the amounts and kinds of the insoluble materials precipitating into an ink or a preservation solution depend on the composition of the ink or the preservation solution. Therefore, even when the rubber materials selected by means of the method of US-A1-2005116984 are employed in the rubber members forming the ink passage, the problem of the precipitation of the insoluble materials occasionally arises. Specifically, the problem may arise when the composition of the ink is adjusted such that the ink has a dynamic surface tension preferable for ejection stability and when the composition of the preservation solution is adjusted such that the preservation solution has a dynamic surface tension preferable for replaceability with the ink and wettability.